A Pakistani man who says he was abused in detention after the September 11 attacks can name the FBI director and a former US attorney-general in his lawsuit against the government, an appeals court ruled.

Javaid Iqbal, a Muslim, was held for more than a year at a Brooklyn detention centre after the September 11 attacks.

He, along with hundreds of Muslims and Arabs sued the US government, claiming they were abused and held for no legitimate reason.

Iqbal says he was subjected to repeated strip searches, beaten, dragged across the floor and that the lights in his cell were kept on 24 hours a day.

The defendants, including FBI Director Robert Mueller and former Attorney-General John Ashcroft, had appealed against a lower court decision that allowed Iqbal's lawyers to seek information on what the officials knew about the abuse.

As part of their efforts to dismiss the case, lawyers for Mueller and Ashcroft argued the officials could not be held personally accountable, but the 2nd US Circuit Court of Appeals disagreed and ruled Ibqal's suit could go forward.

It was "plausible" that Ashcroft and Mueller and other senior Justice Department officials "would be aware of policies concerning the detention of those arrested by federal officers in the New York City area in the aftermath of 9/11", the appeals panel said.

The panel also disagreed with lawyers for Mueller and Ashcroft who argued their actions were reasonable "in the post-9/11 context" and that Iqbal received proper treatment.

The court said while they recognised "the gravity of the situation that confronted investigative officials of the United States as a consequence of the 9/11 attack", Iqbal still had the right to not be harshly treated or discriminated against.

"The exigent circumstances of the post-9/11 context do not diminish the plaintiff's right not to be needlessly harassed and mistreated in the confines of a prison cell by repeated strip and body-cavity searches," the court said.

Iqbal said he lost nearly 18 kilograms and suffered depression after his detention.

Shortly after his release in 2003, he pleaded guilty to having false Social Security papers and writing bad cheques and served time in prison before being deported.

The panel did not rule whether there was any truth to Iqbal's claim that there was no evidence connecting him to terrorism.

US authorities detained 762 non-citizens - almost all Muslims or Arabs - in the weeks after the attacks.

The US government in February paid $US300,000 ($A360,000) to settle with Iqbal's co-plaintiff and fellow detainee Ehab Elmaghraby, an Egyptian, although it did not admit wrong-doing.